HI,Welcome with your query to HCM.
Based on the facts of your query,after its review,In my opinion you Your
dermatologist in his diagnosis and cortizone injections treatment.What you see a active kelloid lumpy red blisterlike lump and not a blister in real terms.
Such blisterlike lumps are of active kelloid growths of fibrous tissue,which could indicate FB of the stitched thread in it.
You have to keep this second possibility of FB
granuloma in external cheek scar in mind, at the red lump you have.In that case Surgical Excision after The USG lump study would fix FB in that lump and would fix your problem.
Hope this reply resolves your worry with your queries.
Will appreciate writing your feedback review comments,to help the needy patients like you at HCM.
Good Day!!
Dr.Savaskar,
Senior Surgical Specialist
M.S.Genl-CVTS